CN115234332B - Comprehensive energy system based on carbon dioxide - Google Patents

Abstract

The present invention relates to a comprehensive energy system based on carbon dioxide, belonging to the field of comprehensive energy systems. The system comprises: a solar PTC subsystem, a power circulation subsystem based on supercritical carbon dioxide, a critical carbon dioxide power circulation subsystem, a cascade refrigeration subsystem and a PEM electrolyzer. The power circulation subsystem based on supercritical carbon dioxide is connected to the solar PTC subsystem, the critical carbon dioxide power circulation subsystem is connected to the power circulation subsystem based on supercritical carbon dioxide, the cascade refrigeration subsystem is respectively connected to the power circulation subsystem based on supercritical carbon dioxide and the critical carbon dioxide power circulation subsystem, and the PEM electrolyzer is respectively connected to the power circulation subsystem based on supercritical carbon dioxide and the critical carbon dioxide power circulation subsystem. The present invention improves the energy efficiency and exergy efficiency of the comprehensive energy system.

Description

A comprehensive energy system based on carbon dioxide

Technical Field

The present invention relates to the field of integrated energy systems, and in particular to an integrated energy system based on carbon dioxide.

Background technique

Fossil fuels are essential in power generation, cooling, heating and other daily life applications. Traditionally, electricity is generated by large power plants, then delivered to the grid and finally to end users. Similarly, most of the cooling effect is generated by electric chillers, where the conventional vapor compression cycle (VCC) is used instead of electricity from the grid. The heating load and hot water production used by domestic and industrial processes can be provided by gas boilers, conventional electric heat pumps or electric heaters. All of these processes are based on separate production systems, which have the disadvantages of high carbon emissions and low fossil fuel utilization. The widespread integration of these systems in the global energy structure has triggered serious greenhouse gas emissions, leading to environmental pollution, climate change and other serious consequences. In addition, as countries develop their economies and their populations grow, energy demand is also increasing. Therefore, it is important, critical and mandatory for the world to turn to renewable energy sources and more efficient energy conversion systems.

High energy costs are forcing many countries, especially developing countries, to utilize low-grade heat as heat/energy for different systems. In addition, waste heat recovery, regeneration, increasing live steam pressure and temperature, reheating and other energy-saving technologies have been applied in many power plants to improve efficiency. Using supercritical CO ₂ (sCO 2 ) gas cycle as a primary power cycle instead of steam Rankine cycle (especially coal-fired power plants) is a promising technology that has attracted much attention. In recent years, studies on sCO ₂ Brayton cycle based systems have emerged and these systems have been evaluated from both thermodynamic and economic perspectives. To improve the design, the exergy, energy and exergy-economic analysis of a solar-driven sCO ₂ power cycle proposed by Abid et al. reported a total energy and exergy efficiency of 30.37% and 32.7%, respectively. The efficiency was improved by 11.6% compared to the conventional system with similar configuration.

Supercritical _CO2 can also be used as a working fluid in solar thermal systems. Qiu et al. analyzed the thermal performance of solar PTCs with _sCO2 as a heat transfer fluid under non-uniform solar flux and found that under typical conditions, solar PTCs can achieve energy conversion efficiencies ranging from 18.78% to 84.17%.

In urban refrigeration systems, CO ₂ is one of the most popular refrigerants due to its high performance and environmental sustainability. An innovative fully integrated transcritical R744 refrigeration system model for supermarkets in warm and hot climates showed that the implementation of direct CO 2 based cooling and heating would result in 33.3% energy savings per year. Moreover, regarding energy consumption, the annual performance of supermarket refrigeration systems using CO ₂ refrigerants in different configurations showed that by using CO ₂ for different refrigeration purposes, the energy consumption of the facility could be reduced by 8.5%. In all these studies, the application of CO ₂ in refrigeration systems has been proven to be feasible.

The two most common low-temperature power cycles are the ORC and Kalina cycles, however, the use of transcritical CO ₂ is another viable option. Through the thermo-economic analysis of a transcritical CO ₂ power cycle and the thermo-economic comparison with the Kalina cycle and ORC low-temperature heat source application, it is found that the net power of the CO ₂ cycle is the largest among the three cycles.

Although there are studies on transcritical and supercritical applications of _CO2 in different power and refrigeration systems, there is a gap in the current research on the integrability and performance of these individual cycles when combined for polygeneration purposes. In the development of polygeneration systems in existing research, the thermodynamic compatibility of different cycles is the basis for the development of these systems.

In summary, the existing energy system has high carbon emissions and low fossil fuel utilization, resulting in low total energy and exergy efficiency of the energy system. Although some individual cycle combinations in the existing technology can improve the total energy and exergy efficiency of the energy system, they cannot improve the energy efficiency and exergy efficiency well when used in a polygeneration system.

Summary of the invention

The object of the present invention is to provide an integrated energy system based on carbon dioxide to solve the problem of low energy efficiency and exergy efficiency when separate cycle combinations are used in a polygeneration system in the prior art.

To achieve the above object, the present invention provides the following solutions:

A CO2-based integrated energy system, comprising: a solar PTC subsystem, a _sCO2 -based power cycle subsystem, a critical _CO2 power cycle subsystem, a cascade refrigeration subsystem, and a PEM electrolyzer;

The solar PTC subsystem is used to collect solar energy and convert it into thermal energy;

The _sCO2 -based power circulation subsystem is connected to the solar PTC subsystem, and the _sCO2- based power circulation subsystem uses the thermal energy to generate electricity and circulate the thermal energy, and part of the thermal energy is input into the critical _CO2 power circulation subsystem;

The critical CO ₂ power cycle subsystem is connected to the sCO ₂ -based power cycle subsystem, and the critical CO ₂ power cycle subsystem uses part of the thermal energy to generate electricity;

The cascade refrigeration subsystem is connected to the _sCO2- based power cycle subsystem and the critical _CO2 power cycle subsystem, respectively, and the cascade refrigeration subsystem is used to perform refrigeration according to the power generated by the _sCO2- based power cycle subsystem and the critical _CO2 power cycle subsystem;

The PEM electrolyzer is connected to the _sCO2- based power circulation subsystem and the critical _CO2 power circulation subsystem respectively, and the PEM electrolyzer is used to produce hydrogen based on the electricity generated by the _sCO2- based power circulation subsystem and the critical _CO2 power circulation subsystem.

Optionally, the sCO ₂ -based power cycle subsystem includes: a first pressure vessel, a high-pressure turbine, a low-pressure turbine, a heat source, and a reheater;

One end of the heat source is connected to the first pressure vessel, and the other end of the heat source is connected to the high-pressure turbine, and the first pressure vessel is connected to the high-pressure turbine; one end of the reheater is connected to the high-pressure turbine, and the other end of the reheater is connected to the low-pressure turbine, and the high-pressure turbine is connected to the low-pressure turbine.

Optionally, a heat exchanger is further included; the critical _CO2 power cycle subsystem is connected to the _sCO2- based power cycle subsystem via the heat exchanger;

One end of the heat exchanger is connected to the first pressure vessel, and the other end of the heat exchanger is connected to the low-pressure turbine.

Optionally, the critical CO ₂ power cycle subsystem includes: a pump, a turbine and a first condenser;

One end of the pump is connected to one end of the heat exchanger, the other end of the pump is connected to the first condenser, the first condenser is connected to the turbine, and the turbine is connected to the other end of the heat exchanger.

Optionally, the cascade refrigeration subsystem includes a high-temperature circulation unit and a low-temperature circulation unit;

The high temperature circulation unit is connected to the low temperature circulation unit through a cascade heat exchanger.

Optionally, the high temperature circulation unit comprises a second pressure vessel, a second condenser and a first valve connected in sequence; the low temperature circulation unit comprises a third pressure vessel, an evaporator and a second valve connected in sequence;

The second pressure device, the first valve, the third pressure device and the second valve are all connected to the cascade heat exchanger;

The second pressure device and the third pressure device are both connected to the turbine.

Optionally, a hot water room is also included;

The hot water chamber is connected to the sCO ₂ -based power circulation subsystem through the heat exchanger; the hot water chamber includes a water inlet and a water outlet, and the hot water chamber is used to produce hot water.

According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

The carbon dioxide-based integrated energy system of the present invention integrates subsystems such as a solar PTC subsystem, a _sCO2 -based power cycle subsystem, a critical _CO2 power cycle subsystem, a cascade refrigeration subsystem and a PEM electrolyzer, uses _CO2 as the main working fluid, and uses a comprehensive thermodynamic modeling program to analyze the overall performance of the carbon dioxide-based integrated energy system and the thermodynamic properties of each subsystem, indicating that the present invention improves the energy efficiency and exergy efficiency of the integrated energy system.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

FIG1 is a structural diagram of a carbon dioxide-based integrated energy system provided by the present invention;

Figure 2 is a bar chart of energy efficiency and exergy efficiency of each subsystem of the integrated energy system;

FIG3 is a graph showing the effect of mass flow rate of solar PTC on thermal energy and fluid temperature;

FIG4 is a graph showing energy efficiency of different solar PTC mass flow rates;

FIG5 is a graph showing the variation of heat input/output and power generation with overall solar irradiance;

FIG6 is a graph showing the effect of different solar radiation on fluid output temperature and solar PTC thermal efficiency;

Figure 7 shows the exergy performance curves of CRS, HWT and the overall system at different ambient temperatures;

Figure 8 is a graph of the exergy performance of the subsystem as the ambient temperature changes.

Detailed ways

The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

The purpose of the present invention is to provide a comprehensive energy system based on carbon dioxide to solve the problems of low power generation and low energy (fire use) efficiency of the _CO2 comprehensive energy system, and to realize the thermodynamic calculation and quantitative research of the _CO2 comprehensive energy system.

In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

Figure 1 is a structural diagram of a carbon dioxide-based integrated energy system provided by the present invention. As shown in Figure 1, the carbon dioxide-based integrated energy system includes: a solar PTC subsystem (parabolic trough collector), an _sCO2 -based power circulation subsystem, a critical _CO2 power circulation subsystem, a cascade refrigeration subsystem, a PEM electrolyzer, a hot water chamber, a heat exchanger, and a cascade heat exchanger.

The solar PTC subsystem is used to collect solar energy and convert it into heat energy. In practical applications, in the solar PTC subsystem, solar energy is collected on the heat collecting pipe through the curved parabolic trough reflector, and the temperature of the heat transfer fluid flowing through the pipe increases and transmits the heat energy to other subsystems.

The sCO ₂ based power cycle subsystem is connected to the solar PTC subsystem, and the sCO ₂ based power cycle subsystem utilizes the thermal energy to generate electricity and circulate the thermal energy, and part of the thermal energy is input into the critical CO ₂ power cycle subsystem.

In a specific embodiment, the _sCO2 -based power cycle subsystem includes: a first pressure vessel, a high-pressure turbine, a low-pressure turbine, a heat source, and a reheater.

One end of the heat source is connected to the first pressure vessel, and the other end of the heat source is connected to the high-pressure turbine, and the first pressure vessel is connected to the high-pressure turbine; one end of the reheater is connected to the high-pressure turbine, and the other end of the reheater is connected to the low-pressure turbine, and the high-pressure turbine is connected to the low-pressure turbine.

In practical applications, the _sCO2 -based power cycle subsystem uses supercritical carbon dioxide _sCO2 as the working fluid as the medium for energy transmission. _sCO2 has good stability and thermal conductivity and is currently the most valued supercritical fluid.

The critical CO ₂ power cycle subsystem is connected to the sCO ₂ -based power cycle subsystem, and the critical CO ₂ power cycle subsystem uses part of the thermal energy to generate electricity.

In a specific embodiment, the critical CO ₂ power cycle subsystem includes: a pump, a turbine, and a first condenser.

The critical _CO2 power cycle subsystem is connected to the _sCO2 -based power cycle subsystem through the heat exchanger; one end of the heat exchanger is connected to the first pressure vessel, and the other end of the heat exchanger is connected to the low-pressure turbine.

One end of the pump is connected to one end of the heat exchanger, the other end of the pump is connected to the first condenser, the first condenser is connected to the turbine, and the turbine is connected to the other end of the heat exchanger.

The cascade refrigeration subsystem is connected to the _sCO2- based power cycle subsystem and the critical _CO2 power cycle subsystem respectively, and the cascade refrigeration subsystem is used to perform refrigeration based on the electricity generated by the _sCO2- based power cycle subsystem and the critical _CO2 power cycle subsystem.

In a specific embodiment, the cascade refrigeration subsystem includes a high-temperature circulation unit and a low-temperature circulation unit; the high-temperature circulation unit is connected to the low-temperature circulation unit through a cascade heat exchanger.

In a specific embodiment, the high temperature circulation unit includes a second pressure vessel, a second condenser and a first valve connected in sequence; the low temperature circulation unit includes a third pressure vessel, an evaporator and a second valve connected in sequence. The second pressure vessel, the first valve, the third pressure vessel and the second valve are all connected to the cascade heat exchanger. The second pressure vessel and the third pressure vessel are both connected to the turbine.

The PEM electrolyzer is connected to the _sCO2- based power circulation subsystem and the critical _CO2 power circulation subsystem respectively, and the PEM electrolyzer is used to produce hydrogen based on the electricity generated by the _sCO2- based power circulation subsystem and the critical _CO2 power circulation subsystem.

The hot water chamber is connected to the sCO ₂ -based power circulation subsystem through the heat exchanger; the hot water chamber includes a water inlet and a water outlet, and the hot water chamber is used to produce hot water.

The working fluid and workflow of the integrated energy system based on carbon dioxide are as follows:

Solar radiation falls on the solar PTC subsystem, and the solar energy is captured and converted into thermal energy through the heat transfer fluid flowing in the PTC tube. This thermal energy will be used for the energy input of other subsequent subsystems to generate electricity or produce hot water, etc. The direction of the arrow in Figure 1 indicates the flow direction of the working fluid. The solar PTC subsystem uses _CO2 as the working fluid, and the generated thermal energy is used as the energy input source of the _sCO2 reheat gas cycle. The compressed _sCO2 obtains energy through the heat source, so that the thermal energy can be transferred between the pipeline of the solar PTC subsystem and the _sCO2 -based power cycle; the _sCO2 fluid is supplied to the high-pressure turbine for power generation. In addition, the low-pressure _sCO2 is heated again through the reheater, and then part of it is transported to the low-pressure turbine to generate more electricity, and the other part returns to the solar PTC subsystem's heat collection pipeline to collect energy again. After power generation, _sCO2 still has a high energy, so most of the _sCO2 is used as a heat source for the critical _CO2 power cycle through the heat exchanger. In the heat exchanger, the pressurized critical _CO2 receives heat and is then sent to the turbine for power generation. The fluid flowing out of the turbine is condensed in the first condenser and then sent to the pump, and the cycle repeats. Part of the heat in the heat exchanger is also sent to the hot water chamber to produce hot water. The electricity generated by the integrated energy system can be used for three different purposes. Most of it (75%) will be fed into the grid, and some (10%) is used to produce hydrogen in the proton exchange membrane (PEM) electrolyzer, which can maximize the power generation and allow the integration of other subsystems in the integrated energy system. The remaining electricity (15%) is used to produce refrigeration with the cascade refrigeration subsystem (CRS). The CRS consists of two independent loops: the high temperature cycle (HTC) and the low temperature cycle (LTC). The CRS uses CO ₂ and ammonia (NH ₃ ) as working fluids, CO ₂ in the low temperature cycle and NH ₃ in the high temperature cycle. In the HTC, the CRS of the second condenser removes heat, and the condensed ammonia expands in the first valve, and then produces a refrigeration effect. The evaporator of the HTC is a cascade heat exchanger, which also serves as the condenser of the LTC. The CO ₂ refrigerant enters the third compressor and is compressed and condensed in the cascade heat exchanger. The condensed _CO2 expands in the second valve and is then passed to the evaporator which produces a refrigeration/cooling effect. Finally, part of the electricity generated is delivered to the user and used in the PEM electrolyzer to electrolyze water to produce hydrogen.

In order to quantitatively study the proposed integrated energy system model, the thermodynamic models of each subsystem are established for simulation verification. The energy and exergy analysis of the modeled system is carried out using a comprehensive thermodynamic modeling program (engineering equation solving program). The specific modeling equations are as follows.

The thermodynamic equations used in modeling the solar PTC subsystem are shown in Table 1:

Table 1 Thermodynamic equations of solar PTC subsystem

Where π = 3.14; _Do is the semi-major axis of the receiver, L is the length of the semi-minor axis of the receiver; _Dg is the semi-major axis of the glass; _Wa is the aperture, _Wg is the diameter of the glass cover; _To is the output temperature, _Ti is the input temperature; Re is the Reynolds number of the fluid in the glass tube; Nu is the Nusselt number; ρ is the density of the fluid in the glass tube, V is the wind speed, μ is the viscosity coefficient; k is a constant; _εg is the emissivity of the glass, σ is the Stefan Bertzmann constant, _Tg is the temperature of the glass, _Ta is the ambient temperature; _Tr is the receiving tube temperature, _εr is the emissivity of the receiver; _Di is the collector diameter, _hfi is the convective heat transfer coefficient in the receiver; m is the mass flow rate, _Cp is the specific heat capacity; S is entropy; _Fr is the receiver heat dissipation coefficient; _Cr is the concentration ratio of the receiver, _Gb is the overall solar radiation, _ηr is the receiver efficiency; _Qs is the solar input; _Tsun is the solar temperature; ΔP is the pressure difference of the fluid, _ρfluid is the density, _Tfluid is the temperature; h is the state enthalpy, h _o is the output enthalpy and S _o is the output entropy.

The input parameters for design, modeling and sizing of the solar PTC subsystem are shown in Table 2; where P _o /P _a represents the ratio of the output pressure to the ambient pressure; ε _r and ε _g are the emissivities of the receiver and glass, respectively; K is the thermal conductivity, T _s is the solar temperature; C is the concentration ratio of the collector, H is the convective heat transfer coefficient; and K _air is the thermal conductivity of air.

Table 2 Solar PTC subsystem size parameters

Other input parameters such as working fluid, turbine rated temperature/pressure, mass flow rate, etc. are highlighted in Table 3.

Table 3 Input parameters of comprehensive energy subsystem

The energy and exergy analysis of the system modeled by the present invention was performed using a comprehensive thermodynamic modeling program (engineering equation solver). In order to study the performance and sensitivity of the comprehensive energy system, the following assumptions were made:

Temperature T ₀ and pressure P ₀ (Table 3) are considered as dead-state characteristics of the system.

The pump, turbine and compressor are considered to be adiabatic.

Ignore changes in potential and kinetic energy in the system.

The operating condition of the system is assumed to be "steady state".

The PTC designed in the present invention is assumed to have the technical performance to work at a temperature above 800K.

Other technical limitations of PTC at extremely high temperatures are considered negligible.

Trigeneration and polygeneration systems in existing literature and applications are mostly driven by fossil fuels. In the present invention, the _CO2 emission reduction (mitigation) effect of the system compared with some fossil fuels is analyzed. This is done by calculating the carbon emitted by different fossil fuel sources. The present invention considers three fossil fuel sources: coal, natural gas and oil. The carbon emission factors used for analysis are shown in Table 4.

Table 4 Carbon emission factors

Compared with the prior art, the benefits of the present invention are as follows: a new integrated energy system based on carbon dioxide has been developed, which integrates subsystems such as a solar PTC subsystem, a _sCO2 -based power circulation subsystem, a critical _CO2 power circulation subsystem, a cascade refrigeration subsystem, a PEM electrolyzer, and a hot water room, and its overall performance and the thermodynamic properties of each subsystem are analyzed. The results show that the invention improves the total energy and exergy efficiency of the integrated energy system.

The present invention models and thermodynamically analyzes the proposed carbon dioxide-based integrated energy system and studies its energy and exergy performance.

According to the solar PTC subsystem design (Table 1) and input parameters (Table 2), it can be obtained that the solar PTC subsystem absorbs 7.72MW of solar energy and converts 4.149MW into useful thermal energy at a temperature of 853.5K; as shown in Figure 2, the energy efficiency and exergy efficiency of the _CO2 -based solar PTC subsystem are 53.75% and 35.63%, respectively, and the energy efficiency and exergy efficiency of the _sCO2- based power cycle subsystem are 12.73% and 8.12%; the energy efficiency and exergy efficiency of the critical _CO2 power cycle subsystem are 16.17% and 5.53%, respectively. The lower exergy efficiency is caused by the temperature difference between the subsystem and the environment and the working fluid; 60% of the thermal energy in this stage is used for the transcritical power cycle, and the remaining 40% is used to produce hot water in the hot water chamber. The calculated exergy efficiency is 44%. 10% of the electricity generated by the power cycle is used for hydrogen production, and 15% will produce refrigeration through the CRS, with a cooling capacity of 180.7 kW. The energy efficiency and exergy efficiency of the PEM electrolyzer are 60% and 20.51%.

The influence of different parameter changes on the performance of different subsystems and the overall performance of the system is tested through parameter analysis. As shown in Figure 3, the sensitivity of the system is tested using three different parameters: mass flow, total solar irradiance and dead temperature of the solar PTC subsystem. T _{out,PTC,MSG-1} represents the fluid output temperature of the solar PTC subsystem. represents the output heat energy of the solar PTC subsystem. The increase of mass flow rate in the solar PTC subsystem will increase the output heat energy, but reduce the fluid output temperature; the increase of mass flow rate in the solar PTC subsystem does not affect the energy efficiency, but will significantly reduce the exergy efficiency, as shown in Figure 4, where η _en,PTC,MSG-1 represents the energy efficiency of the solar PTC subsystem, and η _ex,PTC,MSG-1 represents the exergy efficiency of the solar PTC subsystem. This is because the exergy performance depends on the temperature of the fluid in the system. When the fluid output temperature decreases, the exergy efficiency also decreases accordingly.

In addition, the sensitivity of the performance of the solar PTC subsystem to changes in solar irradiance is examined, as shown in Figures 5 and 6, where represents the output heat energy of the solar PTC subsystem,/> represents the output thermal energy of the solar PTC subsystem, MSG-1 _{Electricity,Prod} represents the electricity production of the solar PTC subsystem, η _en,PTC,MSG-1 represents the energy efficiency of the solar PTC subsystem, η _ex,PTC,MSG-1 represents the exergy efficiency of the solar PTC subsystem, T _{out,PTC,MSG-1} represents the fluid output temperature of the solar PTC subsystem, and when the solar irradiation increases from 500 W/m ² to 1500 W/m ² , the energy efficiency of the solar PTC subsystem increases by 56% (from 16.74% to 72.25%).

Ambient temperature is also called the dead temperature of thermodynamic system, which is one of the factors that most affect the availability of integrated energy system. The sensitivity of the system to the change of dead temperature is studied in the present invention, and the results are shown in FIG7 , where η _ex,CRS,MSG-1 represents the energy efficiency of the solar PTC subsystem, η _ex,HWT,MSG-1 represents the exergy efficiency of the solar PTC subsystem, and η _{ex,MSG-1,with,PTC} represents the overall exergy efficiency of the solar PTC subsystem. It can be seen that the change of ambient temperature has little effect on the overall exergy efficiency, but it will affect the exergy performance of different subsystems (CRS, HWT); in addition, with the increase of ambient temperature, the exergy efficiency of sCO ₂ power cycle, critical power cycle and PEM electrolyzer all decreases, as shown in FIG8 , where η _ex,PEM,MSG-1 represents the exergy efficiency of PEM electrolyzer, η _{ex,sCO2,MSG-1} represents the exergy efficiency of sCO ₂ power cycle subsystem, and η _tCO2,MSG-1 represents the exergy efficiency of critical power cycle subsystem.

Although the invention is described herein with reference to embodiments of the invention, it should be understood that other modifications and implementations may be devised by those skilled in the art that will fall within the scope and spirit of the principles disclosed herein. More specifically, within the scope of the disclosure, drawings, and claims of the present application, a variety of improvements may be made to the modeling and analysis of integrated energy systems. In addition to improvements to system modeling and analysis, other uses will be apparent to those skilled in the art.

The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

This article uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims (7)

1. A carbon dioxide-based integrated energy system, comprising: a solar PTC subsystem, a sCO ₂ -based power cycle subsystem, a critical CO ₂ power cycle subsystem, a cascade refrigeration subsystem, and a PEM electrolyzer;

the solar PTC subsystem is used for collecting solar energy and converting the solar energy into heat energy;

The power circulation subsystem based on the sCO ₂ is connected with the solar PTC subsystem, the power circulation subsystem based on the sCO ₂ generates power by utilizing the heat energy and circulates the heat energy, and part of the heat energy is input to the critical CO ₂ power circulation subsystem;

The critical CO ₂ power circulation subsystem is connected with the sCO ₂ -based power circulation subsystem, and the critical CO ₂ power circulation subsystem utilizes part of the heat energy to generate power;

The cascade refrigeration subsystem is respectively connected with the sCO ₂ -based power circulation subsystem and the critical CO ₂ power circulation subsystem, and is used for refrigerating according to the power generated by the sCO ₂ -based power circulation subsystem and the critical CO ₂ power circulation subsystem;

The PEM electrolyzer is respectively connected with the power circulation subsystem based on sCO ₂ and the critical CO ₂ power circulation subsystem, and is used for preparing hydrogen according to the power generated by the power circulation subsystem based on sCO ₂ and the critical CO ₂ power circulation subsystem.

2. The carbon dioxide-based integrated energy system of claim 1, wherein the scco ₂ -based power circulation subsystem comprises: a first compressor, a high pressure turbine, a low pressure turbine, a heat source, and a reheater;

One end of the heat source is connected with the first pressure device, the other end of the heat source is connected with the high-pressure turbine, and the first pressure device is connected with the high-pressure turbine; one end of the reheater is connected with the high-pressure turbine, the other end of the reheater is connected with the low-pressure turbine, and the high-pressure turbine is connected with the low-pressure turbine.

3. The integrated carbon dioxide-based energy system of claim 2, further comprising a heat exchanger; the critical CO ₂ power cycle subsystem is connected with the scco ₂ -based power cycle subsystem through the heat exchanger;

One end of the heat exchanger is connected with the first pressure device, and the other end of the heat exchanger is connected with the low-pressure turbine.

4. The carbon dioxide-based integrated energy system of claim 3, wherein the critical CO ₂ power cycle subsystem comprises: a pump, a turbine, and a first condenser;

one end of the pump is connected with one end of the heat exchanger, the other end of the pump is connected with the first condenser, the first condenser is connected with the turbine, and the turbine is connected with the other end of the heat exchanger.

5. The carbon dioxide-based integrated energy system of claim 4, wherein the cascade refrigeration subsystem comprises a high temperature circulation unit and a low temperature circulation unit;

the high-temperature circulating unit is connected with the low-temperature circulating unit through a cascade heat exchanger.

6. The integrated carbon dioxide-based energy system of claim 5, wherein the high temperature circulation unit comprises a second pressure vessel, a second condenser, and a first valve connected in sequence; the low-temperature circulating unit comprises a third pressure device, an evaporator and a second valve which are connected in sequence;

The second pressure device, the first valve, the third pressure device and the second valve are all connected with the cascade heat exchanger;

the second and third presses are both connected to the turbine.

7. The integrated carbon dioxide-based energy system of claim 3, further comprising a hot water chamber;

The hot water chamber is connected with the power circulation subsystem based on the sCO ₂ through the heat exchanger; the hot water chamber comprises a water inlet and a water outlet, and is used for preparing hot water.